After virtual directory re-creation I have checked its modules in IIS and made sure, that Kerberos module is native and the path to its DLL is correct:

Root cause 3:

There is a missing Windows feature WinRM IIS extension.The full description is here: http://technet.microsoft.com/en-us/library/dd759166.aspx This was the case in my lab and I feel it is the side effect of in-place upgrade of OS from Windows server 2012 to Windows Server 2012 R2 on Exchange server (Yes I know it is not good idea, but how to learn non standard issues in other way). Here is simple solution: Install this windows feature:

Get-WindowsFeature *IIS* #to check if it is installed
Add-WindowsFeature Winrm-IIS-Ext # to install

Exchange 2010 / 2013 can be designed so, that multiple mailbox tiers can be placed within one database. In this case there is not easy way how to control mailbox limits for bigger companies. I wrote the script, which can help managing limits based on single value in Custom attribute 12.

There is a Microsoft service called ExRAP. (Exchange health check) and one of the errors in report, provided to you as a result of ExRAP is that internal DNS records are not checked automatically on all DNS servers. I have made a script, which will do DNS records monitoring for you and in case records differs from designed values, it will send e-mail to predefined e-mail address.
Prerequisites:
You must have rights to connect to DNS server and read DNS zones using WinRM.